more tests and more coverage

install.go

@@ -45,22 +45,18 @@ User=nobody
 WantedBy=multi-user.target
 `, exePath)
 
-	if err := os.WriteFile(systemdPath, []byte(serviceContent), 0644); err != nil {
+	if err = os.WriteFile(systemdPath, []byte(serviceContent), 0644); err != nil {
 		return err
 	}
 
 	// Enable and start the service
-	if err := runCommand("systemctl", "daemon-reload"); err != nil {
-		return err
-	}
-	if err := runCommand("systemctl", "enable", serviceName); err != nil {
-		return err
-	}
-	if err := runCommand("systemctl", "start", serviceName); err != nil {
-		return err
+	if err = runCommand("systemctl", "daemon-reload"); err == nil {
+		if err = runCommand("systemctl", "enable", serviceName); err == nil {
+			err = runCommand("systemctl", "start", serviceName)
+		}
 	}
 
-	return nil
+	return err
 }
 
 var run = func(cmd *exec.Cmd) error {

install_test.go

@@ -6,6 +6,8 @@ import (
 	"os/exec"
 	"reflect"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestInstallDefaultConfig(t *testing.T) {
@@ -63,6 +65,9 @@ func TestGetMachineID(t *testing.T) {
 
 	// Replace the machine-id file path
 	oldMachineIDPath := "/etc/machine-id"
+	pathMachineID = "/"
+	assert.Equal(t, "", getMachineID())
+
 	pathMachineID = tempFile.Name()
 	defer func() { pathMachineID = oldMachineIDPath }()
 
@@ -75,6 +80,8 @@ func TestGetMachineID(t *testing.T) {
 }
 
 func TestInstallSystemdService(t *testing.T) {
+	assert.NoError(t, run(exec.Command("ls")))
+
 	// Create a temporary file for the systemd service
 	tempFile, err := os.CreateTemp("", "test_systemd_service")
 	if err != nil {

main_test.go

@@ -61,13 +61,21 @@ func TestRun(t *testing.T) {
 	err = do()
 	assert.NoError(t, err)
 
+	var lastServer *socks5.Server
+	oldListenAndServe := listenAndServe
+	defer func() {
+		listenAndServe = oldListenAndServe
+	}()
 	*flagInstall = false
 	*flagDaemon = true
-	listenAndServe = func(_ *socks5.Server, network, addr string) error {
+	listenAndServe = func(server *socks5.Server, network, addr string) error {
+		lastServer = server
 		return fmt.Errorf("testing without starting server (%v:%v)", network, addr)
 	}
+	assert.Error(t, oldListenAndServe(lastServer, "", ""))
+
 	err = do()
-	assert.Error(t, err, "failed to start server: testing without starting server (tcp:0.0.0.0:1080)")
+	assert.Error(t, err)
 	listenAndServe = func(_ *socks5.Server, _, _ string) error {
 		return nil
 	}